Los Angeles daily herald., 1887-09-09


have earthenware house drains less
than six inches in diameter, on ac
count of the frequency Of stoppages il
they are made smaller, and the street
pipes should, for obvious reasons, have
somewhat larger size. The grades
given to the eight-inch pipes can, in
most cases, be at least six inches pei
100 feet, which is ample to secure d
cleansing velocity of the water. Fol
convenience, all eight-inch and ten
inch pipes and over have been de-
signed as main or intercepting sewers
according to their function.
BRICK SEWERS.
1t is preferable to construct sewers
over eighteen inches in diameter, oi
brick, instead of using pipes, and as
brick sewers can readily be built to
any desired form at no greater ex-
pense, it is advisable to make them
egg-shaped instead of circular for the
following reason: The large capacity
OF the sewers will for some years cause
them to run with comparatively little
water. Therefore, the contracted in
vert of the egg-shape will give a great
er concentration to the flow than the
circular, and cause better current
during this interval and less chance
for deposit.
The depth at which sewers should
be placed below the street, when it is
not governed by the necessity for OBJ
tanning desirable grades, is matter
which rests with the local desire.
Where it is wished to drain cellars a
depth of about twelve feet will be re-
quired; otherwise six feet is usually
sufficient.
In order to have ready access to any
part of the system, both for the pur-
pose of inspection and cleaning, it is
desirable to build manholes at inter-
walls of from 200 to 400 feet, according
to the size and grade of the sewer.
The smaller the pipe and the flatter
the grade, the closer must they be
placed, and between them all pipes up
to twelve inches in diameter must be
laid perfectly straight in line and
grade, so that their entire length can
be inspected at any time, and all bends
and turns must be made inside of the
manholes. Sewers of fourteen inches
and over are not found to require this
restriction, and they should be curved
when necessary with as large radius
as possible. The manhole cover must
be perforated for ventilation, and in
order to avoid any matter from drop
ping into the sewer, a silt pan is sus-
pended below it and the cover is Sc
curely locked. When passing through
the manhole the sewer should be
neatly curved, and when several pipes
Join, the junction should be made with
great care to avoid eddies, and, there
ore, the accumulation of deposit.
NECESSARY VENTILATION.
The necessity for ventilation rises
mainly from the fluctuations in the
flow Of the sewage. In order to pre-
vent a consequent compression and
rarifaction of the air in the pipes,
which would cause the forcing of traps
connected with the house drains, a
free communication with the atmos-
phere must be provided for it, and an
escape where it cannot be noticed or
do any harm. The usual and best
way to accomplish this is by perforat
ing the covers of the manholes. An
other method is to provide for circu-
lation through the house drains. The
latter is not generally favored in our
country, and it is considered far pre-
ferable to place trap between the
sewer and house drains, and establish
an independent ventilation for the
latter. In this way any defects in the
house drain or plumbing will not cause
air from from the street sewer to enter
the building.
To maintain sewer system in a
proper condition, it is necessary to
give it a periodical flushing Differ
ence of custom prevails in different
cities as to its required frequency, va
rying from daily to annual flushing.
When automatic appliances are re-
sorted to for the purpose, this period
must be short-say daily, otherwise it
is not limited. In general, it should
vary with the conditions. Small sew
ers with flat grades, or such that are
not much used, require more frequent
cleaning than others. Once a week is
considered in England sufficiently
often to keep ordinary sewers perfectly
clean.
In some of the best sewer systems,
the flushing is done monthly, and in
others the period is still longer.
DAILY FLUSHING.
do not consider a daily flushing
necessary. and therefore advise the
placing OF automatic flush tanks only
at such points where it may be found
ineXpedient or more expensive to
clean the sewers otherwise. In some
cases it will be found preferable to
use the manhole at the head of a
sewer as flush tank, and to fill it
whenever found necessary from the
adjoining Waterman and to discharge
it by hand. In other cases it will be
found practicable, by suitable valves
placed in the manholes, to allow the
sewage from larger sewers to be turned
into lower-lying branches for certain
length of time. In still other cases
the sewer can be connected with the
irrigation bitches and flushed from
them when desired 1t should be left
to the judgment OF the engineer exc
cutting the work to select the best
means in each case.
The drainage of houses forms an
essential part of every sewerage sys-
tenn, and should be constructed in har-
mony with the same. AS already
stated. the main drain should not ex-
ceed six inches in diameter, which is
enough for the largest hotel, and un-
less made OF iron pipe and laid with
good grade, it should not be of a
smaller size, as otherwise stoppages
frequently occur. The house drain,
further, should have a main trap and
a properly de yised system of ventila-
ton to avoid the unsealing OF the
smaller traps at the fixtures.
The danger to health in having i'm
properly arranged pipes and fixtures
within the building, has caused many
cities to adopt general plumbing regu-
lations, to license plumbers and to
have a general plumbing inspector, as
A.